Cleanup serverjre8 branch on isle-tomcat & isle-ubuntu-basebox

[bseeger]

Issue description

Both the isle-tomcat and isle-ubuntu-basebox have a few git branches that are either not being used or should be merged back to master.

Right now it seems as if isle-tomcat:serverjre8 github is meant to be the main branch and that ISLE 1.1 was built off of it. Here's the commit that's linked to the isle-tomcat container shown in the ISLE images folder: https://github.com/Islandora-Collaboration-Group/isle-tomcat/commit/2714f21e840c4bd13f8805e1f22cada7b607105e

The rest of the images seem to be created from the dockerfiles on the master branches in github.

isle-ubuntu-basebox has a few extra branches as well that can probably go away (serverjre8, serverjdk8) as I think they are development.

So, the general task of this ticket is to merge back the serverjre8 branch to master in isle-tomcat (which may happen via the v1.1.1 release as that release was built off of the correct (serverjre8) branch) and to cleanup any branches no longer being used in the other repo - or at least document why they exist and what their ongoing use might be.

Expected changes

• that master will be the main branch for each repo - so that tagged releases can be created from there.
• that any unused branches will get deleted
• documentation created for any branches, other then master, that we feel should still exist.

[noahwsmith]

[1.1.2 - high priority, low effort]

[bseeger]

PR For tomcat: https://github.com/Islandora-Collaboration-Group/isle-tomcat/pull/3 I think we also need to delete the isle-tomcat:serverjre8 branch after that PR is accepted.